Abstracts Brochure - CERN

MOPCH050
MOPCH051
MOPCH052
MOPCH053
26-Jun-06 16:00 - 18:00 MOPCH — Poster Session
Observation of Resonant Diffusive Radiation in Random Multilayered Systems
Diffusive radiation generated by the pas-
Zh.S. Gevorkian (YerPhI)
sage of electrons of energy 200KeV-2.2MeV
through a random stack of films has been observed
in the visible light region. The resonant feature of radiation is revealed. The observed yield and the angular
dependence are in agreement with the theoretical predictions.
Operation of the First Undulator-based Femtoslicing Source
S. Khan, K. Holldack, T. Kachel, T. Quast (BESSY GmbH) R. Mitzner
(Universität Muenster, Physikalisches Institut)
60
At the BESSY II storage ring, a source of sub-
100-fs x-ray pulses with tunable polarization
and excellent signal-to-background ratio has
been constructed in 2004, based on laser-in-
duced energy modulation ("femtoslicing"*) and subsequent angular separation of the short-pulse x-rays from an
elliptical undulator. After commissioning and characterizing the source, short-pulse radiation is now routinely delivered
for pump-probe applications. The paper summarizes the results from commissioning and operational experience
as well as possible upgrade options.
*A. Zholents and M. Zoloterev, PRL 76 (1996), 912.
Shaping Sub-picosecond X-ray and THz Radiation Pulses
S. Khan, K. Holldack, T. Quast (BESSY GmbH) R. Mitzner (Universität
Muenster, Physikalisches Institut)
The energy modulation of electrons in a storage
ring by femtosecond laser pulses allows
to generate x-ray pulses ("femtoslicing"*) as
well as far-infrared (THz) pulses with sub-
picosecond duration. Their shape can be controlled by shaping the initial laser pulses, producing e.g. double pulses,
pulse trains** or any arbitrary shape. Double pulses may be useful for THz-THz or x-ray-THz pump-probe applications.
Simulations show the generated pulse shapes, taking into account laser-electron slippage and other lengthening
effects.
*A. Zholents, M. Zoloterev, PRL 76 (1996), 912.**J. Byrd, ICFA Workshop on Short Bunches, Frascati 2005.
Towards Sub-picoseconds Electron Bunches: Upgrading Ideas for BESSY II
G. Wuestefeld, W. Anders, J. Feikes, J. Knobloch, P. Kuske (BESSY
GmbH)
Sub-picoseconds bunches were achieved
with the BESSY low alpha optics, and their
lengths were measured using Fourier Transform
spectroscopy*. To avoid the coherent
synchrotron radiation instability, the current in these short bunches has to be limited to theµampere level. An upgrade
of the BESSY II rf gradient to much larger values is suggested to overcome this low current limitation by two
orders of magnitude. Intense, picoseconds long bunches could then be achieved already at the regular user optics.
The resulting short and very intense electron bunches are useful for generation of short x-ray pulses and powerful
THz-radiation. Expected parameters of bunch length and current are discussed.